Question regarding the semicolon

Question

My first language is Norwegian, and even in my own language I'm always slightly uncertain if I'm using semicolons correctly. I think I know the rules, but there's always a niggling doubt whether I apply them correctly (if that makes sense).

Here are a few examples where I've used them:

1. NATO’s intervention in Libya was authorised by the UNSC; in Kosovo it was not.

2. Such a claim is obviously politically motivated, and borders on legal absurdity; the ban on the use of force is accepted as jus cogens binding all states, not simply a treaty obligation between two parties where one breach excuses another.

3. I don’t know which parts might be relevant, but check the other sections when you’re done writing to see if there are theories, facts etc. that you don’t use in your analysis; if there are, consider leaving them out.

As I understand it, a semicolon can be used in place of a full stop, when the latter part points to something in the first. E.g. "They weren't hungry; I was starving". Is this the case or have I got it wrong? If it is, and some of the examples are wrong, what am I missing?

Thanks for any feedback

Answer 1

The semicolon works well in your first example, and is unobjectionable in your third.

For your second example I would prefer a colon.

Where there's a sense that two things are being contrasted or compared, a semicolon works well; where the second half of the sentence is an elaboration or explanation of the first half, a colon works better. See https://www.lexico.com/grammar/colon (How to Use a Colon: "between two main clauses in cases where the second clause explains or follows from the first") and https://www.lexico.com/grammar/semicolon (How to Use a Semicolon: "between two main clauses that balance each other and are too closely linked to be made into separate sentences").